Hack-saw machine



B. L. CALKINS.

HACK SAW MACHINE.

APPLICATION FILED MAY 21, 1 920.

1,437,225. Patented Nov. 28, 1922.

2 SHEETSSHEET I.

awbntoz 156-; z z, cazzvm B. L. CALKINS.

HACK SAW MACHINE.

APPLICATION FILED MAYZI. 1920.

Patented N 0v. 28, 1922.

2 SHEETS-SHEET 2.

,BertZ. 62227725 Patented Nov. 28, 1922.

BEETIQCALKINS, or BACINE, WISCONSIN.

HACK-SAW MACHINE.

Application filed May 21,

,To all whom it may concern:

Be it known that I, BERT L. GALKLNS, a citizen of the United States of America, re-

siding at Racine, in the county of Racine and State of lVisconsin, have invented certain new and useful:Improvements in Hack- Saw Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to hack saw ma.- chines and similar machines of that ty-pein which the reciprocating frame that the'car ries the saw blade or other cutting tooltis fed towards the work during the forward or cutting stroke thereof and is relieved from pressure and is lifted to clear the teeth from the work during the return stroke. Among the objects of the invention are; first, the obtaining of a constant rate of feedof the saw blade to and through the work at a constant pressurev underuniform resistance; second, the variation in pressure to correspond with increasing or decreasing crosssection of the work; third, the retraction of the blade to clear the work during the return or non-cutting stroke; fourth, the accomplishment of these effects by a hydraulic unit. With these objects in view the invention comprises the novel. construction as hereinafter set forth.

In the drawings:

Figure 1 is a diagrammatic:sideelevation of a hack saw -machine, to which my improvements are applied;

Figure 2 is a longitudinal section showing the hydraulic feeding and controlling mechanism;

Figure 3Iis an enlarged section through a portion of the apparatus.

A is a suitable bed on which -is mounted the crank shaft B having the crank C thereofconnected by a rod Dwith the reciprocat ing frame E for holding the-hacksaw blade F. The frame E is slidablymounted on guide bearings G upon a rockable frame H" pivotally secured at I to a standard J rising from the bed. This frame H is' moved to carry the hack saw towards or from the work by a hydraulic mechanism ofthe following construction:

K is a cylinder containing a piston L hav-. ing a rod L extending upward therefrom and'connected tothe frame H by suitable means, such as the roller bearing L on the rod engaging a slot L in the frame. The slotcL provides a bearing surface for the 1320. Serial N0. 383,097.

roller bearing L fol-operating the frame H, and is elongated to provide clearance forthe angular movement of the frame H aboutt'he pivot-I. M is an outer receptacle surrounding or' at one side of the cylinder K and containlng a supply of the fluid which is used in said cylinder. N and O are cylindriqcal passages which respectively connect the chamberswithin the cylinderK on opposite sides of the piston with the receptacle M, andcN and O are plungers in said cylindrical passages. Theplunger N is actuated in timed relation to. the reciprocation of theframe E,'preferably by'acam P arranged upon the crank 'shaftand engaging a. roller Q. mounted in the adjustable collar Q" on said plunger. Movement of the plunger in the reverse direction is effected by a spring R sleeved thereon, one end. abutting against a collar R adjustably secured: to the plunger, and the other end: abutting against a member R -which is adjustable in abearing B on the stationaryframe. The plunger N controls a passage N preferably formed within the plunger itself, and connecting the chamber within the cylinder K with the receptacle M. This passage includes alaterally opening port N in the plunger, which, when the plunger is at the inner end of its stroke, may or may not be sealed by being located within the cylindrical passage N, but during the outward movement of the plunger, said port N will register wit'h'the receptacle M so as to establish communication between this receptacle andthe cylinder K. The check valveN permits the "flow of fluid through the port N from the receptacle M into thecylinder K," but prevents any reverse flow. I 1

The plungerO is also provided With a passage O therein, which, when the plunger is at'the inner end of its stroke, is sealedwithin the cylindrical passage 0, but when said plunger is moved outward, will establish communication between the cylinder "K and the receptacle M. is a spring for actuating the plunger-O inward, and O is an adjustable stop on theplunger for limiting its inward movement.

lVit'h the construction as thus "far described, the rotation ofthe camlP in cooper ation with the spring R will cause the reciprocation of the plunger N and themovement is so timed with the reciprocation of the frame E that the plungerN will be movedinward in relation the cylinder K stance,

during the cutting stroke of the saw and will be moved outward during or just preceding the return stroke. The inward movement of the plunger N, which is effected by the pressure of the spring R, will cause a displacement of fluid above the piston L, which will effect a downward movement of said piston, thereby drawing down the rod L and rocking downward the frame H. The amount of movement is determined by the setting of a stop S on the plunger N and this is so adjusted as to give just the desired feed for the cut. he downward movement of the piston L will displace liquid from the chamber below said piston, which will be forced out through the passages O and 0 into the receptacle M. Upon the further movement of the cam P the plunger l will beaetuated in the reverse direction, outward from the cylinder K. This, by relieving pressure of the fluid in said cylinder above the piston, will permit the pressure of the spring 0 exerted on the piston O and from the latter upon the fluid below the piston L to raise said piston a sufficient distance toprovide proper clearance for the saw during its return stroke. The amount of this lifting of the piston is determined by the setting of the stop 0 and after the limit is reached, the further outward movement of the piston N will cause the flow of fluid. through the passage i 2 from the receptacle M into the cylinder K above the piston. Thus when, during the succeeding inward stroke of the plunger N, the additional fluid within the cylinder K above the piston will cause a further depression of the piston or a further downward feeding of the saw, and this operation is continued until the work is completely severed by the saw.

The operation as above described will effeet a uniform feeding of the saw into the work on its cut-ting stroke and a uniform clearance for the saw upon its return stroke. It is, however, pressure should be varied according to the cross-section which is being out. For inif the saw is used to sever a bar of round stock, the cross-section will progressively increase in length from the beginning of the cut to half-way through the stock and will then progressively diminish" until the stock is completely severed. T have provided means for varying the pressure corresponding to the variation in cross-section and preferably of the following construct-ion;

T is an air chamber connected with the cylinder K and having a check valve T in the connecting port, which permits the escape of fluid from the cylinder into said. chamber, but prevents the return. During the initial feeding movement, a portion of the fluid displaced by the plunger N during its initial movement will pass by the check valve T andfinto the chamber T, thereby ward pressure of the desirable that the feeding lessening the feeding pressure of the saw upon the work. As the chamber T fills up with the displaced fluid, the pressure of the air therein constantly rises until finally it will prevent further ingress of the fluid. This, therefore, will have the effect of progressively increasing the pressure of the saw upon the work from the beginning of its out until it reaches a full hearing. The reverse action of diminishing the pressure as the saw approaches the completion of its cut is accomplished by placing upon the rod L a spring L engaging a stationary abutment and a collar L on said rod. Thus as the piston L is fed downward, the collar L will come into contact with the spring L and in the further downward movement, the tension of this spring will be increased progressively and will re-act to oppose the down piston L, so that the pressure of the saw on the work will be diminished.

Where the machine is used for cutting work to irregularly varying cross-section variation of the pressure may be accomplished by manual adjustment, as, for instance, by providing the chamber T with a fluid escape cock T which may be adjusted to permit a slight escape of the fluid and thereby diminish the pressure and rate as desired. The chamber T is also providedwith an air cock T which, when open in conjunction with the valve T will drain the liquid from the chamber T and thus secure an air supply as desired.

Upon the completion of the downward feeding movement through the work, it is desirable to provide means for automatically returning the saw ready for engagement with new work. This is accomplished by a trip mechanism, which opens a bypass around the piston Lbetween the chambers on opposite sides thereof in cooperation with a spring U for moving the piston and rod upward. tached to a lever U fulcrumed upon a link U andhaving its opposite end connected to the rod L. The trip mechanism for opening the by-pass comprises a by-pass valve V for normally closing the by-pass port, this being arranged between passages V and V COHIIGCtIH res ectivelv wlth the chambers on opposite sides of the piston.

feeding As shown, the spring U is at- The valve V is connected to a lever W,

which is normally locked from movement by 2 a latch W engaging a stop VV This latch is disengaged by a rod X which'extends into the path of the downwardly moving frame The arrangement is such that just at the completion of the varying cut, the frame bearing upon the rod X will trip the latch W, permitting a spring V to open the valve V and by-pass the fluid. Thereupon the tension of the spring U operating through the lever U and rod L will raise operation.

lVhat I claim as my invention is: 1. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprising a cylinder: a piston in said cylinder, a connection between said piston and said reciprocating cutting tool for feeding the latter towardsthe \VOIlQ IDGQDS for displacing the fluid in said cylinder on one side of said piston to operatethe piston, means for ntroducing lnto said cylinder on the same .sideof' said piston successive predeterminedvolumes of fluid to cause sa d displacingimeans to advance the piston step by step, means connected to said cylinder on the opposite side of said piston, permitting the displacement therefrom of equal volumes of fluid. and means for reintroducing into the cylinder a portion of the displaced volume and thereby displacing a corresponding amount of fluid from the first-mentioned side of the piston.

2. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprising a cylinder, a piston therein, a connection between said piston and tool for applying and relieving pressure on the latter towards the work, means for displacing the fluid in said cylinder to actuate said piston, means for introducing into the cylinder on one side of said piston successive predetermined volumes of fluid to cause a step-by-step advancement of said piston, means permitting the displacement of an equal volume of fluid from the cylinder on the opposite side of the piston, and means for yieldably resisting the displacement of said fluid and for re-introducing a portion of each displaced volume upon relief of pressure on the fluid in the cylinder on the opposite side of said piston, and means for relieving said pressure during the non-cutting stroke, whereby pressure on the tool is simultaneously relieved.

3. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprising a cylinder, a piston therein, means for applying pressure to the tool connected with said piston, a receptacle for a supply of fluid under atmospheric pressure, means for successively introducing into said cylinder on one side of said piston predetermined volumes of fluid derived from said receptacle, means on the opposite side of said piston for displacing a correspond ing volume of fluid into said receptacle, means'for re-introducing a portion of the displaced fluid during the non-cutting stroke of the tool and for displacing a corresponding volume from the cylinder on the firstmentioned side of the piston.

4. The combination with a reciprocating cutting tool, of hydraulic feeding means therefor comprising a cylinder, a piston therein, and means operated by said piston for applying pressure to said tool during its cutting stroke, a receptacle for fluid under atmospheric pressure, a plunger moving in a passage between said receptacle and cylinder on one side of the piston for successively displacing predetermined vol umes of fluid and actuating said piston stepby-step; a second plunger operating: in a passage between said cylinder on the opposite side of said piston and said receptacle,

resilientyicldable means for pressing said second plunger towards said cylinder, a stop for limiting the movement of said" plunger in its passage, whereby the fluid displaced by saidpiston will be forced through the passage against the resistance-of said plunger into said receptacle, and a portion of said volume will be re-introduced into the cylinder to move the piston oppositely,

means for reciprocating said first-mentioned plunger, and means operating during said reciprocation for admitting into said cylinder on the first-mentioned side of the piston a volume of fluid'equal to that permanently displaced "from the opposite side of said piston.

5. The combination with a reciprocating cutting tool, of hydraulic feeding means therefor comprising a cylinder, a piston therein, and means operated by said piston for applying pressure to the tool, means for applying a yieldable force to said piston in a direction to relieve pressure upon said cutting tool, means for displacing the fluid in said cylinder on one side of the piston to actuatesaidpiston, means for successively introducing into said cylinder on the same side of the piston predetermined volumes of fluid to cause a step-by-step advancement of said piston in a direction to apply pres sure to the work, means permitting the displacement of a corresponding volume of fluid from the opposite side of said piston, and means operating at the completion of the cutting operation for opening a by-pass between the chambers in said cylinder on opposite sides of the piston, whereby the constantly applied pressure will return the piston to its initial position.

6. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprising a cylinder, a piston therein, means operated by said piston for applying pressure against said tool, a receptacle for fluid under atmospheric pressure, means operated below the level ofthe fluid in said receptacle for successively introducing into said cylinder on one side of said piston predetermined volumes of fluid derived from said receptacle, means permitting the displacement of corresponding tion of the displaced volume to move said piston in the opposite direction and to relieve pressure upon said tool during the non-cutting stroke.

7. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprising a cylinder, a piston therein, means operated by said piston for applying pressure against said tool, means for displacing the fluid in said cylinder on one side of said piston to actuate the piston, means for successively introducing into said cylinder on the same side of the piston predetermined volumes of fluid to cause a step-by-step advancement of said piston, means permitting the displacement of an equal volumeof fluid from the cylinder on the opposite side of the piston, and means for reintroducing into the cylinder on said opposite side of the piston a portion of the displaced'fiuid to actuate said piston'in the opposite direction, thereby relieving the pressure and retracting the cutting tool during the non-cutting stroke.

8. The combination with a reciprocating cutting tool, of hydraulic means for feeding the same, comprisinga cylinder, a piston therein, means operated by said piston for applying pressure against said tool, means for displacing the fluid in said cylinder on one side of said piston to actuate the piston, means for successively introducing into said cylinder on the same side of the piston predetermined volumes of fluid to cause a step-by-step advancement of said piston, means permitting the displacement of an equal volume of fiuid from thecylinder on the opposite side of the piston, means for reintroducing into the cylinder on said opposite side of the piston a portion of the displaced'fiuid to actuate said piston in the opposite direction, thereby relieving the pressure and retracting the cutting tool during the non-cutting stroke, and manually adjustable means for regulating the amount of displacement of the fluid to reduce the Weight of feed and the feeding pressure of the cut during any part of the operation.

' In testimony whereof I afiix my signature.

BERT L. CALKINS. 

